1. Field of the Invention
The invention relates in general to an electronic device and method of manufacturing the same, and more particularly to an electronic device with shielding structure from crosstalk, noise and interferences, and method of manufacturing the same.
2. Description of the Related Art
When two circuits are side-by-side with each other, crosstalk and interference may occur if the operation frequencies of the circuits are high, especially at above RF frequency which is about a few tens of megahertz to several gigahertz or even higher. This kind of problem is especially severe if various kinds of circuits are integrated on the same substrate. For an example, in a typical system on chip (SOC) floor plan, radio frequency circuits such as a low noise amplifier (LNA) may sit next to high-speed logics or a power amplifier. Under such a situation, the performance and linearity of the LNA is usually degraded by crosstalk or interferences from the high-speed logic circuits or the power amplifier.
FIG. 1 is a schematic diagram of possible leakage paths of the crosstalk and interferences in a conventional radio frequency integrated circuit (RFIC). A RFIC 100 includes a silicone substrate 102, an active circuit 104 such as a LNA, and noisy sources 106, such as high speed logics or power amplifiers. The active circuit 104 and noisy sources 106 are disposed on the silicone substrate 102 and located adjacent to each other. Conventionally, crosstalk or interferences between the active circuit 104 and noisy sources 106 may be occurred both through the air or the silicone substrate 102 as shown in FIG. 1.
In case that the noisy sources 106 are high speed logics, the fast rise and fall time of their high-speed logic signals may contain many harmonics. If the high speed clock is a few tens or a few hundred megahertz, its fundamental frequency signal or harmonics may fall into the RF signal bands of the active circuit 104, and the small RF signal of the active circuit 104 will then be inevitably contaminated by these harmonics.
In case that the noisy sources 106 are power amplifiers, they usually generate RF signals with much larger power than that of the signal received by the active circuit 104. Once these large signals leak to the input of the active circuit 104, they may compress the active circuit 104, degrade its linearity, and cause more inter-modulations.
As a result, the crosstalk or interferences may degrade the signal integrity and circuit performance, and the performance degradation is especially severe in a SOC device in which various kinds of circuitries (RFIC, high-speed logic and analog circuits etc) are integrated on a single substrate.